Functional Java Tuples

Just a prototype so far:

The generic types of the arguments are always A, B, C, etc. The result is of generic type R.

It’s my goal to have three forms:

  • Method/Lambda Form: Takes n arguments
  • Curried Form: Methods are chained A -> B -> C -> ... -> R
  • Uncurried Form: Takes a tuple (A,B,C,...) -> R

The idea is to add all the basic functions of Haskell to a project that then uses to have a way of using tuples for functional programming in Java 8.

  • curry / uncurry
  • zip / unzip
  • composition (“.”-operator in Haskell)
  • pipes (“|>” in F#)
  • partial application
  • fn.arity() returns the arity of the function.
  • Convert Suppliers and Consumers to Functions.

There’s still a lot to do…

List of TODOs:

  • Implementations of Fn for Quad ... Decade
  • Unit-Tests (instead of
  • Types Curried and Uncurried for such forms of the methods

Contact me on github if you are interested in this project.

Why a Consumer is not a Function.

java.util.function.Consumer does not extend java.util.function.Function. But what if you want a set of both types? Why isn’t there a ConsumerFunction?

A ConsumerFunction is not defined in java.util.function. You can easily do it yourself. But you will see that it’s not that simple. void is a keyword in Java. There is a class Void and (by reflection) you can even get an instance of Void. But you have to use a return statement to get a Function.

Continue reading “Why a Consumer is not a Function.”